1. Field of the Invention
The invention relates in general to a semiconductor device, and more particularly to a semiconductor device having composite functions.
2. Description of the Related Art
Along with the advance in the development of semiconductor, a VDMOS (vertical diffused MOS) is provided. The VDMOS is a device used for amplifying or switching electronic signals. In the VDMOS, a voltage on an oxide-insulated gate can induce a conducting channel between the two other contacts called source and drain. The channel can be of n-type or p-type, and is accordingly called an n-VDMOS or a p-VDMOS. It is by far the most common transistor in both digital and analog circuits, though the bipolar junction transistor was at one time much more common.
However, if a driving voltage is only applied on the drain/source, the VDMOS cannot be worked on. The VDMOS must be applied driving voltage on both of the drain/source and the gate to be worked on. Therefore, the function of VDMOS is limited in its application.